Television.

`Seaquest' Produces Newest Heartthrob

His "seaQuest DSV" action figure is new in toy stores and selling briskly.

Pictures of him run through and through-and through-the pages of Teen Beat, Bop and Big Bopper.

Fan letters from young girls pour in by the thousands each week.

In the face of all this, Jonathan Brandis can't help but have idol thoughts. He's the latest fave rave, the ultimate boy-toy for junior high girls. Brandis, who turned 18 last month, has gotten hot enough to make veritable dorks of fading adorables Mark-Paul Gosselaar ("Saved By the Bell") and Joey Lawrence ("Blossom"). He's already the subject of two unauthorized Big Bopper biographies, each containing 32 pages of essential info. The first is subtitled "Cuddly, Cozy & Caring," and the sequel is "More Babe For Your Buck."

Brandis, who plays computer genius Lucas Wolenczak on "seaQuest," is at home in Los Angeles when a 46-year-old former Annette Funicello freak asks him about all of this.

"The teen magazines are going to use you whether or not you want to be in them," he says. "They just stick you in there. I just kind of accept that and go along with them and cooperate. I just kind of feel guilty if I don't do something."

On the day of the interview, Brandis, the only child of Mary and Greg Brandis, is scheduled to have a summit of sorts with idol-emeritus Kirk Cameron of "Growing Pains." Together they are making a girl's dream come true in cooperation with the Make A Wish Foundation.

"He was so huge!" Brandis exclaims. "I'm going to ask him about that. You've got to expect that it's going to end."

Brandis' TV career dates to 1982, when he had a recurring role as a 6-year-old on the soap "One Life to Live." He and his parents moved from New York to Los Angeles in 1986. Guest roles were plentiful, in shows ranging from the mini-series "Poor Little Rich Girl" to the syndicated sitcom "The Munsters Today."

Then came "Ladybugs," a 1992 big-screen comedy starring Rodney Dangerfield. Brandis' character masqueraded as a member of a girls soccer team coached by Dangerfield.

"I thought it was going to be a funny movie, but I never realized that so many young girls would fall in love with it. After that, everything really changed," Brandis says.

"A lot of young people were really watching my stuff. That's one reason why I make really safe choices. I'm kind of at an age where I want to cater to the kids in a way."

Bop's Rodgers says that most of his magazine's core readership-girls between 10 and 16-look for "non-threatening," vulnerable, sensitive cuties to adorn their bedroom walls and scrapbooks.

"A lot of things that girls at that age crave, they don't really see in the boys they go to school with," he says. "Most boys at that age are not really comfortable expressing the sensitive side of their personality."

Brandis also won the hearts of some boys with the 1993 movie "Sidekicks," in which he teams with Chuck Norris. The editors of both Teen Beat and Big Bopper describe Brandis as "very cooperative."

"He's one of the rare breed of actors who actually feels some sense of loyalty to his fans," Rodgers says.

While awaiting word on whether "seaQuest" will be renewed for a second season, Brandis has collected the show's new line of miniature toy figures. He gives his own a mixed review.

"Look at my thighs, for God's sake. I'm like The Hulk!" he says. "But the hair is pretty cool. I guess they did a good job."

During his time off from "seaQuest," he'll travel to Prague, Czech Republic, this spring to play the title role in The Family Channel's "Good King Wenceslaus."

"It's a sort of Robin Hood film," he says.

On Sunday, Brandis and "seaQuest" co-star Roy Scheider will co-host the NBC-Ch. 5 special "Masters of Illusion: The Wizards of Special Effects."

Dad is his agent and Mom tries to cope with all the mail. Brandis says he'll occasionally phone a fan to say thanks.

"I try to answer as much mail as I can," he says, "but there's really no way. My mom's, like, going crazy, but she's doing a great job. I don't know how she does it."

Meanwhile, the editors of Teen Beat, Big Bopper and Bop are hoping Brandis' mail piles up at least a mile high. His continued hotness means more newsstand sales; circulation is roughly about 200,000 for each edition of the magazines, the editors say.

In seemingly medieval times-1976-the first issue of Teen Beat had John Travolta and Donny and Marie Osmond on the cover. Eight years later, Bop premiered with cover photos of John Stamos, Adam Ant and Scott Baio. All are collective Lawrence Welks to today's tweens and early teens.

But Jonathan Brandis . . . the current issues of Teen Beat and Big Bopper both claim to have exclusive first-hand accounts of his earthquake experience.